From 07ae044b0dd4968b4ef6dd072cc0a2a851d79902 Mon Sep 17 00:00:00 2001
From: Earlopain <14981592+Earlopain@users.noreply.github.com>
Date: Fri, 8 May 2026 21:10:27 +0200
Subject: [ruby/prism] Take the strings encoding as the initial encoding in the
 ripper translator

When no magic encoding comment is present, it does not default to utf-8,
and takes the encoding of the string that contains the source code instead.
Most of the time that will be utf-8, but not always.

https://github.com/ruby/prism/commit/1a273db780
---
 lib/prism/translation/ripper.rb | 5 +++--
 test/prism/ruby/ripper_test.rb  | 6 ++++++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/lib/prism/translation/ripper.rb b/lib/prism/translation/ripper.rb
index ddcec997b9..f179a149a1 100644
--- a/lib/prism/translation/ripper.rb
+++ b/lib/prism/translation/ripper.rb
@@ -57,7 +57,8 @@ module Prism
       #          [[1, 13], :on_kw,     "end", END      ]]
       #
       def self.lex(src, filename = "-", lineno = 1, raise_errors: false)
-        result = Prism.lex_compat(coerce_source(src), filepath: filename, line: lineno, version: "current")
+        coerced = coerce_source(src)
+        result = Prism.lex_compat(coerced, filepath: filename, line: lineno, version: "current", encoding: coerced.encoding)
 
         if result.failure? && raise_errors
           raise SyntaxError, result.errors.first.message
@@ -4077,7 +4078,7 @@ module Prism
 
       # Lazily initialize the parse result.
       def result
-        @result ||= Prism.parse(source, partial_script: true, version: "current", freeze: true)
+        @result ||= Prism.parse(source, partial_script: true, version: "current", freeze: true, encoding: source.encoding)
       end
 
       def line_and_column_cache
diff --git a/test/prism/ruby/ripper_test.rb b/test/prism/ruby/ripper_test.rb
index 05be087868..4fff630561 100644
--- a/test/prism/ruby/ripper_test.rb
+++ b/test/prism/ruby/ripper_test.rb
@@ -224,6 +224,12 @@ module Prism
       assert_equal(Ripper.tokenize(source), Translation::Ripper.tokenize(source))
     end
 
+    def test_encoding
+      source = '"わたし"'.encode(Encoding::Windows_31J)
+      assert_equal(Ripper.tokenize(source), Translation::Ripper.tokenize(source))
+      assert_equal(Ripper.sexp(source), Translation::Ripper.sexp(source))
+    end
+
     def test_sexp_coercion
       string_like = Object.new
       def string_like.to_str
-- 
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